Brake for vehicles



Aug. 28, 1923. 1,466.549

F. H. ROYCE BRAKE FOR VEHICLES Filed Oct. 10 1922 Frederick 06km) ca.

Patented Aug. 28, 1923.

UNITED STATES PATENT OFFICE.

FREDERICK HENRY ROYCE, OF DERBY, Eld'GLAND, ASSIGNOR TO ROLLS ROYCE LIMITED, OF DERBY, ENGLAND, A COMPANY OF GREAT BRITAIN.

BRAKE FOR VEHICLES.

Application filed October 10, 1922. Serial 170. 598,543.

four-wheeled vehicles with a brake on each wheel, said brakes being brought into operation by a pedal or other appliance.

A common methodof constructing brakes 1 for the wheels of vehicles is to attach a drum.

' to each of the wheels to be braked and to provide within the rim or periphery of the drum an annular metal ring directly or 1n-.

directly attached to the frame of the vehicle so as not to be rotatable, with normally a small clearance between the rim or periphcry of the drum and the ring and with some mechanical means whereby the ring can be expanded and caused to come into contact 2 with the rim or pgriphery of the drum. In the common form the ring is made in two equal parts or sections commonly. called shoes, two adjacent ends of the sections being hinged while the other two adjacent ends can be forced apart to cause a general expansion of the circumference of the ring.

, In brakes hitherto in vogue the expansion of the ring has'been efl'ected mechanically or through the instrumentality of apneumatic or fluid medium.

One of the difiiculties of a braking syst especially when it operates on all our wheels of the vehicle and is pedal-operated, is that in order to provide a suflicient clearance of the brake shoes when-the brake is in the off position, while at the same time securing a good leverage of mechanical advantage between the pedaland the brake shoes, an excessive and ineonveniently large movement of the pedal lever is necessary.

Proposals have been made to. overcome this d'ifliculty by utilizing or bringing into play some other force in substitution for the force exerted by the driver who then only has to move a lever or other appliance are connected tq a mechanism whereby they.

for actuating the mechanism. For the purposes of road vehicles, it is of reat importance that the driver shall eel from the moment he puts on the brake a direct resistance, bearing a constant ratio to the pressure being exerted on the shoes; and the exigencies of a four-wheel road vehicle render it imperative or highly desirable that the pedal and valve controlling the pneu matic force should be located away from and be independent of the pressure cylinder or cylinders directly actuating the brake shoes. But in most of these devices the driver does not feel the brake'pressure which is being applied and it is rendered more diflicultfor 'him to adjust it accordingly.

The object of this invention is to overcome this difliculty and to provide an improved mechanism for actuating the brakes.

. According to this invention a source of pneumatic or fluid pressure is provided and is applied through the action of a special valve operated by a pedal or other up liance to. actuate the brake mechanism wlth the force required, and synchronously offering to the movement of the valve mechanism a resistance of a predetermined ratio to the force applied to the brake mechanism, so that although the driver by a comparatively small movement of the lever can bring to bear all the force required, hestill feels the extent of the force applied and the adjust ment of the degree of pressure is facilitated.

Anexample of the lnvention is shown in sectional diagram in the accompanying at a. .a is a lever moving on a fulcrum, a

and having extensions a in which are drawing in which, a designates the rim of formed recesses to take the ends of connecting members a which are hinged to the other ends of the shoes.

b designates a pressure cylinder In which is a piston 12 connected by the connectin rod b to the aforesaid lever a. and pivote thereto at b". c designates an electric motor operating a pump 0 which through the pipe.

0 efi'ects compression of-air in the reservoir d.

The valve mechanism comprises a cylinder 0 having an exhaust port 6 and an inlet port e and containing a hollow cylindrical piston 6 with corresponding ports e and e. f designates a foot pedal connected to or tormedas an extension of the piston c". The cylinder 6 and pedal f are held in a sleeve g (to which the cylinder 6 is rigidly attached) with a flange which is supported in the tootboard it of the vehicle. 7 designates a helical spring by which the pedal, when released, is returned to its normal position and 2' and a" are pipes connecting the reservoir 05 and pressure cylinder 5 respectively to the cylinder 6.

Normally the ports a and e register and no pressure is exerted on the brake mecha nism. When the pedal is depressed these ports are brought out or" register and are closed while further depression of the pedal causes the port 6 to register with the port c Directly the ports e and e are in register, pressure is applied to the cylinder 7), and to the reverse side of the piston e in cylinder 6. This pressure is always below the pressure in the reservoir 07 owing to leakage or" air past the pistons b and '6 and hence the degree of pressure in the cylinder l) and that applied to the shoes, and the pressure against the piston e are dependent on the extent to which the port e is open. The ratio of pressure exerted on the brake shoes and the pressure exerted against the piston e is dependent on the mechanical advantage oi the leverages secured by the lever a and the ratio of the cross sectional area of the piston b to that of the piston 6 it is not necessary to have a separate pressure cylinder for each brake. @ne such cyltill inder could be arranged with mechanical connections to the different brakes. ther, the invention is not limited to the particular kind of brake described. lt could be applied to various other forms.

It has been proposed in connection with brakes for cranes and such like, and in which a pneumatic force is applied, to so arrange the mechanism that when the pneumatic force is applied, a resistance is'felt by the operator; but in one form of mechanism through the instrumentality of a metal spring, and in another form with the valve as part of the same unit as the pressure cyl inder directly operating the brake.

lit has also been proposed in a brake for road vehicles to apply pneumatic force and to so arrange the mechanism that when the force is applied, resistance is felt by the driver, but through the instrumentality of a metal spring.

None of these mechanisms or arrangements would effect the ends of my invention which are specially re uired in reference to road vehicles, to'wit: t at when the pressure is applied, it directly resists the action of the operator, and that the resistance ofiered is Furincense in ratio to the force applied to the brake, and that the system is so composed as to render this practicable in a road vehicle.

What 1 claim as my invention and desire to secure by Letters Patent of the United States is l. A pneumatic operating system, comprising a source of fluid pressure; a valve mechanism embodying a cylinder having inlet and exhaust ports in its walls, a hollow, cylindrical piston having inlet and exhaust ports adapted to be brought into and out of registration with the corresponding firstnamed ports, and an operating element connected to said piston; a pressure cylinder; a piston therein; conduit leading from the source of pressure to the inlet port of the valve cylinder; and a separate conduit leadins; from the valve cylinder to the pressure cylinder for supplying pressure to thelatter cylinder to operate the piston therein 2. A pneumatic operatingsystem, comprising a source of fluid pressure; a valve mechanism embodying a cylinder having inlet and exhaust ports in its walls, a hollow cylindrical piston having inlet and exhaust ports adapted to be brought into and out of registration with the corresponding first named ports, and an operating element to which the piston is directly and rigidly connected; a pressure cylinder; a piston in the pressure cylinder mechanically connected to the part to be operated; a conduit leading from the source oi pressure to the inlet port all of the valve cylinder; and a separate conduit leading from the valve cylinder to the pressure cylinder for supplying pressure to the latter cylinder to operate the piston therein.

3. In a pneumatic operating system, the

combination of a source of fluid pressure; a valve mechanism embodying a cylinder having an inlet port and separate exhaust and delivery ports, the exhaust port opening into the atmosphere, a hollow cylindrical piston having inlet and exhaust ports, means normally holding the piston in a position in which its inlet and exhaust ports are respectively disposed out of and in register with the corresponding cylinder ports, and an operating element for moving said piston into a position wherein its said inlet and exhaust ports are respectively alined with and disalined from the corresponding cylin der ports; a conduit leading from the source of pressure to the cylinder inlet port; and a separate conduit leading from the cylinder delivery port to the part to be operated.

d. In a pneumatic operating system, the combination ofa source of dead pressure; a valve mechanism embodying" a cylinder having an inlet port and separate exhaust and delivery ports, the exhaust mrt opening into the atmosphere, -hollow cylindrical piston having inlet and exhaust ports, and a spring- 1 controlled operating element/to which said disalined from the corresponding cylinder piston is directly and rigidly connected, norports; a conduit leading from the source of 10 mally holding the piston in a position in pressure to the cylinder inlet port; and a which its inlet and exhaust ports are respecseparate conduit leading from the cylinder 5 tively disposed out of and in register with delivery port to the part to be operated.

' the corresponding cylinder ports but de- In witness whereof I have signed this pressible into a position in which said pisspecification.

ton ports are respectively alined with and FREDERICK HENRY ROYCE. 

